Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
  • C08J9/0061—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof characterized by the use of several polymeric components
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J3/00—Processes of treating or compounding macromolecular substances
  • C08J3/24—Crosslinking, e.g. vulcanising, of macromolecules
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L23/10—Homopolymers or copolymers of propene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L53/00—Compositions of block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers
  • C08L53/02—Compositions of block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers of vinyl-aromatic monomers and conjugated dienes
  • C08L53/025—Compositions of block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers of vinyl-aromatic monomers and conjugated dienes modified
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2323/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
  • C08J2323/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2453/00—Characterised by the use of block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Derivatives of such polymers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2203/00—Applications
  • C08L2203/14—Applications used for foams
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L23/16—Ethene-propene or ethene-propene-diene copolymers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2312/00—Crosslinking
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L53/00—Compositions of block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L53/00—Compositions of block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers
  • C08L53/02—Compositions of block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers of vinyl-aromatic monomers and conjugated dienes

Definitions

• thermoplastic elastomer (TPE) materials Thermoplastic elastomers are broadly defined as rubber-like materials that, unlike conventional vulcanized rubbers, can be processed and recycled like thermoplastic materials, yet have properties and performance similar to that of vulcanized rubber at service temperatures.
• the invention more specifically relates to thermoplastic vulcanizates (TPV), which are thermoplastic elastomers with a cross-linked rubbery phase produced by the process of dynamic vulcanization.
• the thermoplastic vulcanizates of the invention are foamed materials produced by physical or chemical blowing agents, wherein processing characteristics and foam properties are improved by the inclusion of a modifier derived from styrene block copolymers.
• the invention also relates to foamed articles obtainable by the process of the invention.
• thermoplastic vulcanizate compositions especially those based on polyolefin thermoplastic resins, which have good foaming properties, and on processes for producing foams having improved properties.
• U.S. Pat. No. 5,070,111 discloses a process of foaming thermoplastic vulcanizate compositions using water as the sole foaming agent.
• U.S. Pat. Nos. 5,607,629 and 5,788,889 both incorporated herein by reference, describe methods for the production of foamed thermoplastic vulcanizate profiles by extrusion with a water blowing agent.
• thermoplastic elastomer compositions which incorporate styrenic elastomers.
• Published European Patent Application No. 0 860 465 teaches a method of foaming thermoplastic vulcanizates using a water containing chemical compound which releases water at temperatures above the melting point of the thermoplastic vulcanizate.
• Published European Patent Application 0 872 516 discloses the use of polypropylene resins having specific rheological properties to enhance the foaming performance of olefinic thermoplastic vulcanizates.
• the problems of providing thermoplastic elastomer foams which are soft, with good surface smoothness, low water absorption, improved compression set and compression load deflection, and having fine and uniform cell structure have not been overcome by the prior art.
• the present invention is based on the discovery that superior thermoplastic vulcanizate foams can be produced by incorporating into the thermoplastic vulcanizate, prior to foaming, a hydrogenated styrenic block copolymer.
• a hydrogenated styrenic block copolymer is used to produce a very soft foam product having a number of desirable attributes, including improved processability, high melt strength, high cell density and uniformity, smooth surface, low water absorption, with improved compression set and compression load deflection.
• the present invention relates to a process for foaming a thermoplastic vulcanizate using a physical or chemical blowing agent, wherein a hydrogenated poly(styrene-jb-isoprene- ⁇ -styrene) block copolymer (SEPS) is incorporated into the thermoplastic vulcanizate composition prior to foaming. Sufficient SEPS is incorporated to be effective in achieving the desired attributes.
• the invention also encompasses thermoplastic vulcanizate compositions containing the SEPS, foamed articles prepared therefrom, and to the use of SEPS to improve said foams.
• the invention relates to a process for preparing a foamed thermoplastic vulcanizate, comprising the steps of blending
• Thermoplastic resins suitable for use in the compositions of the invention include thermoplastic, crystalline polyolefin homopolymers and copolymers. They are desirably prepared from monoolefin monomers having 2 to 7 carbon atoms, such as ethylene, propylene, 1-butene, isobutylene, 1-pentene, 1-hexene, 1-octene, 3- methyl-1-pentene, 4-methyl-1-pentene, 5-methyl-1-hexene, mixtures thereof and copolymers thereof with (meth)acrylates and/or vinyl acetates. Preferred, however, are monomers having 3 to 6 carbon atoms, with propylene being most preferred.
• polypropylene includes homopolymers of propylene as well as reactor and/or random copolymers of propylene which can contain about 1 to about 30 weight percent of ethylene and/or an alpha-olefin comonomer of 4 to 16 carbon atoms, and mixtures thereof.
• the polypropylene can have different types of molecular structure such as isotactic or syndiotactic, and different degrees of crystallinity including materials with a high percentage of amorphous structure such as the "elastic" polypropylenes.
• polystyrene resins which can be used in the invention, are high, low, linear-low and very low-density polyethylenes, and copolymers of ethylene with (meth)acrylates and/or vinyl acetates. These polyolefins include both linear or branched polymers.
• the polyolefins mentioned above can be made using coordination polymerization catalyst systems, such as conventional Ziegler/Natta catalysts, or by single site catalyst systems, such as metallocene catalysts, and as well by other known means of olefin polymerization, such as free-radical polymerization.
• coordination polymerization catalyst systems such as conventional Ziegler/Natta catalysts
• single site catalyst systems such as metallocene catalysts
• other known means of olefin polymerization such as free-radical polymerization.
• Commercially available polyolefins may be used in the practice of the invention.
• the amount of thermoplastic polyolefin resin found to provide useful thermoplastic elastomer compositions is generally from about 8 to about 90 weight percent.
• the thermoplastic polyolefin content will range from about 9 to about 60 percent by weight.
• Suitable rubbers include non-polar, rubbery copolymers of two or more alpha- monoolefins, preferably copolymerized with at least one polyene, usually a diene.
• Saturated monoolefin copolymer rubber for example ethylene-propylene copolymer rubber (EPM) can be used.
• EPM ethylene-propylene copolymer rubber
• unsaturated monoolefin rubber such as EPDM rubber is more suitable.
• EPDM is a terpolymer of ethylene, propylene and a non-conjugated diene.
• Satisfactory non-conjugated dienes include 5-ethylidene-2- norbornene (ENB); 1 ,4-hexadiene; 5-methylene-2-norbomene (MNB); 1 ,6-octadiene; 5-methyl-1 ,4-hexadiene; 3,7-dimethyl-1 ,6-octadiene; 1 ,3-cyclopentadiene; 1 ,4- cyclohexadiene; dicyclopentadiene (DCPD); and vinyl norbornene (VNB).
• ENB 5-ethylidene-2- norbornene
• MNB 5-methylene-2-norbomene
• VNB vinyl norbornene
• butyl rubbers are also useful in the thermoplastic vulcanizate compositions.
• the term butyl rubber includes copolymers of an isoolefin and a conjugated monoolefin, terpolymers of an isoolefin with or without a conjugated monoolefin, divinyl aromatic monomers and the halogenated derivatives of such copolymers and terpolymers.
• Another suitable copolymer within the scope of the olefin rubber of the present invention is a copolymer of a C 4 . 7 isomonoolefin and a para-alkylstyrene, and preferably a halogenated derivative thereof.
• the amount of halogen in the copolymer, predominantly in the para- alkylstyrene, is from about 0.1 to about 10 weight percent.
• a preferred example is the brominated copolymer of isobutylene and para-methylstyrene.
• Natural rubbers are also olefin rubbers suitable for use in the thermoplastic elastomer composition.
• the amount of rubber in the thermoplastic vulcanizate generally ranges, from about 92 to about 10 weight percent.
• the rubber content will be in the range of from about 40 to about 91 weight percent.
• the thermoplastic vulcanizate may optionally contain reinforcing and non- reinforcing fillers, plasticizers, antioxidants, stabilizers, rubber processing oils, extender oils, lubricants, antiblocking agents, antistatic agents, waxes, foaming agents, pigments, flame retardants and other processing aids known in the rubber compounding art.
• Such additives may comprise up to about 70 weight percent, more preferably up to about 65 weight percent, of the total composition.
• Fillers and extenders which can be utilized include conventional inorganics such as calcium carbonate, clays, silica, talc, titanium dioxide, carbon black and the like.
• the rubber processing oils generally are paraffinic, napthenic or aromatic oils derived from petroleum fractions. The oils are selected from those ordinarily used in conjunction with the specific rubber or rubber component present in the composition. Processing
• the rubber component of the thermoplastic vulcanizate is generally present as small, i.e. micro size, particles within a continuous thermoplastic resin matrix, although a co-continuous morphology or a phase inversion is also possible depending upon the amount of rubber relative to thermoplastic resin and the degree of vulcanization, if any, of the rubber.
• the rubber is at least partially vulcanized, and most preferably it is fully vulcanized (crosslinked).
• thermoplastic olefin polymer or thermoplastic resin
• olefin rubber or cross-linkable elastomer
• vulcanizing the rubber elastomer
• the rubber be crosslinked by the process of dynamic vulcanization.
• dynamic vulcanization means a vulcanization or crosslinking (curing) process wherein the rubber is vulcanized under conditions of shear at a temperature above the melting point of the thermoplastic resin component.
• Crosslinking (curing) agents include sulfur, sulfur donors, metal oxides, phenolic resin systems, maleimides, peroxide based systems, hydrosilylation systems, high energy radiation and the like, both with and without accelerators and co-agents.
• fully vulcanized or completely vulcanized as used herein mean that the olefin rubber component of the composition has been crosslinked to a state in which the elastomeric properties of the crosslinked rubber are similar to those of the rubber in its conventional vulcanized rubber state.
• the degree of crosslinking (or cure) of the rubber can also be expressed in terms of gel content, crosslink density or amount of uncrosslinked rubber that is extractable by a rubber solvent. All of these descriptions are well known in the art.
• a typical partially crosslinked composition will have less than about 50 to less than about 15 weight percent of the elastomer extractable by a rubber solvent, while a fully crosslinked composition will have less than about 5 weight percent, and preferably less than about 3 weight percent, of the elastomer extractable by a rubber solvent.
• thermoplastic vulcanizates are rubbery materials having tensile set values of about 50% or less, which meet the standards for rubber as defined by ASTM D1566.
• the composition of the invention includes a hydrogenated styrene block copolymer component.
• This component is generally described as a hydrogenated poly(styrene- ⁇ -isoprene- -styrene) block copolymer (SEPS).
• SEPS hydrogenated poly(styrene- ⁇ -isoprene- -styrene) block copolymer
• One such material particularly suited for use in the process of the invention is SeptonTM 2002, available from Septon Company of America Inc., a Kuraray Group company.
• the amount of the SEPS component in the composition of the invention generally ranges from about 1 to about 10 weight percent, based on the total weight of the composition including the thermoplastic resin component, the rubber component, additives and the SEPS component.
• the preferred amount of SEPS ranges from about 1 to about 10 weight percent, with about 2 to about 4 weight percent being most preferred.
• the amount of SEPS can be expressed in terms of parts per hundred parts of rubber (phr).
• the preferred amount of SEPS, expressed in this manner, ranges from about 3 to about 40 phr with a range of about 5 to about 15 phr being most preferred.
• the SEPS was generally incorporated directly into the thermoplastic resin/rubber blend during production of the thermoplastic vulcanizate, in a one step process, so that it was an integral part of the composition. Since the SEPS block copolymer is hydrogenated it contains very low levels of unsaturation and does not co-cure with the elastomer component during dynamic vulcanization. It is believed that the SEPS remains as a discrete phase in the thermoplastic vulcanizate. Alternatively, the SEPS can be mechanically blended with a preformed thermoplastic vulcanizate composition, or it can be introduced into the foaming process simultaneously with the thermoplastic vulcanizate.
• thermoplastic vulcanizates were prepared from blends of polypropylene thermoplastic resin and EPDM rubber, with common additives and processing aids. SEPS was incorporated into the blends and the rubber component was cross-linked by dynamic vulcanization using a phenolic resin cure system to prepare the vulcanizates.
• the thermoplastic vulcanizate was introduced into a single screw extruder and thoroughly melted. The blowing agent, water in the examples set forth in Table 1 , was then injected under pressure into the molten thermoplastic elastomer at rates of 1.1 to 1.4 weight percent. The melt was mixed and conveyed, under pressure, to the extruder exit and through a shaping die.
• the hot and fragile foam was transferred to a conveyor belt where it was cooled by air and water mist.
• the foamed article may then be cut or shaped for specific applications.
• Foamed profiles can be either extruded alone as described or coextruded with a dense carrier.
• the specimen was allowed to remain thus submerged for either 24 hours at atmosperhic pressure, or for five minutes at 26 inches Hg vacuum (above the surface of the water). After the appropriate time, the specimen was removed, blotted dry, weighed and the percent change in mass was calculated.
• the foamed thermoplastic elastomer of the invention provides a smooth surface, low water absorption, good compression set and improved compression load deflection. Visual inspection shows that foam cell density is high and the cells are uniform in structure.
• thermoplastic elastomer formulation with 35 phr polypropylene
• Foams were generated from the compositions thus prepared, using various levels of water as the blowing agent in order to obtain foams with various densities.
• the thermoplastic elastomer and foam properties were evaluated, and the results are set forth in Tables 2 and 3.
• thermoplastic vulcanizates of Table 1 were EPDM rubber - VistalonTM 3666 (ExxonMobil Chemical Co.); polypropyene - D008MTM (Aristech Chemical Corp.); process oil - SunparTM 150M; clay - Icecap KTM (Burgess); curative - SP-1045TM (Schenectady International); carbon black -
• Ampacet 49974 (Ampacet Corp.); branched polypropylene - HMS 130D (Borealis).
• the foamed thermoplastic vulcanizate composition and the molded and shaped articles made therefrom are useful in a variety of applications such as handles and grips for tools or utensils, as well as weather strip for automotive and construction uses.

Landscapes

• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
• Compositions Of Macromolecular Compounds (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (2)

Family

ID=31888276

Family Applications (2)

Family Applications After (1)

Country Status (4)

Cited By (6)

Families Citing this family (12)

Family Cites Families (11)

• 2003
  • 2003-08-01 WO PCT/US2003/024326 patent/WO2004016678A2/en not_active Ceased
  • 2003-08-01 JP JP2004529241A patent/JP5091388B2/ja not_active Expired - Fee Related
  • 2003-08-01 EP EP03788319A patent/EP1534772B1/en not_active Expired - Lifetime
  • 2003-08-15 AU AU2003268106A patent/AU2003268106A1/en not_active Abandoned
  • 2003-08-15 WO PCT/US2003/025560 patent/WO2004016679A2/en not_active Ceased

Also Published As

Similar Documents

Legal Events